Speeding on Melbourne's Western Ring Road is proving irresistable for the lead-footed.

New police figures reveal that 30,000 motorists were caught speeding in the six weeks after the reactivation of fixed speed cameras at Keilor Park Drive near the Calder overpass last month.

Worryingly, 160 motorists were detected travelling 25km/h over the 80km/h posted speed limit, and six were caught doing 45km/h above the limit.

The cameras had originally been deactivated in 2010 while infrastructure works were carried out by VicRoads.

Signs had been installed in the weeks leading up to the reactivation of the cameras, and remained in place for the six weeks after.

“Since the cameras were reactivated, compliance at this site has been 97.9 per cent,” Superintendent Neville Taylor said.

“This is compared to 99.9 per cent at other fixed speed camera sites across the state. It’s just not good enough."

The reactivation of the cameras followed a month-long testing period, which saw 1253 motorists detected travelling more than 25km per hour over the speed limit. No infringements were issued during the testing period.